President Obama is proposing to begin a vast expansion of the U.S. health-care system by creating a $634 billion reserve fund over the next decade, launching an overhaul that most experts project will ultimately cost at least $1 trillion.

The "reserve fund" in the budget proposal being released today is Obama's attempt to demonstrate how the country could extend health insurance to millions more Americans and at the same time begin to control escalating medical bills that threaten the solvency of families, businesses and the government.

Obama aims to make a "very substantial down payment" toward universal coverage by trimming tax breaks for the wealthy and squeezing payments to insurers, hospitals, doctors and drug manufacturers, a senior administration official said yesterday.

Embedded in the budget figures are key policy changes that the administration argues would improve the quality of care and bring much-needed efficiency to a health system that costs $2.3 trillion a year.

By first identifying a large pot of money to underwrite health-care reform -- before laying out a proposal on who would be covered or how -- Obama hopes to draw Congress to the bargaining table to tackle the details of a comprehensive plan. The strategy is largely intended to avoid the mistakes of the Clinton administration, which crafted an extensive proposal in secret for many months before delivering the finished product to lawmakers, who quickly rejected it.

"We aim to get to universal coverage," administration budget aide Keith Fontenot told health-care activists last night. Obama is "open to any ideas people want to put forward. He wants to work openly with the Congress in a very inclusive process."

Virtually every major player in the health-care sector will find something to object to in Obama's plan, an intentional decision made in the hope that "a little bit of pain" will be offset by the appeal of insuring millions more people, said one White House adviser.

About half the money for the new fund would come by capping itemized tax deductions for Americans in the top income bracket. The proposal, which administration officials characterize as a "shared-responsibility issue," would reduce the value of tax deductions for families earning more than $250,000 by about 20 percent, according to administration documents.

Nearly one-third of the money would be generated by eliminating subsidies that the government pays insurers that sell Medicare managed-care plans. Instead, the Medicare Advantage plans would be put under a competitive bidding process, for a savings of $175 billion over the next decade.

"The administration believes it's time to stop this waste," according to the documents.

Even before the budget proposal became public, the Obama team began selling it to groups that will be central to the upcoming debate. Top lawmakers were brought to the White House for briefings, while constituency groups heard the highlights in an evening conference call yesterday.

"This is the first step towards getting health-care reform done this year," White House domestic policy adviser Melody C. Barnes told allies in one call. "We can't underestimate the importance of rallying around this budget. It serves as a footprint for something bigger."

During the campaign, Obama promised to reduce the number of uninsured Americans, improve the quality of care and save the typical family $2,500 a year in medical costs.

"We know that this is not enough to achieve our overall goal of getting health care for every American, but it is a significant down payment," Neera Tanden, a top Obama health adviser, said during a conference call.

Given the economic crisis and the soaring federal deficit, many had begun to fear that health reform would be postponed, said Drew Altman, president of the nonprofit Kaiser Family Foundation.

"What this does is, it allows the train to move forward," he said. "But there are still big issues to work out about how to reform health care and how to come up with the rest of the money."

Many of the targeted savings are familiar and controversial.

If the tax-deduction cap is enacted, it is likely to hit many small businesses, said House Republican Leader John A. Boehner (Ohio).

"Everyone agrees that all Americans deserve access to affordable health care," he said, "but is increasing taxes during an economic recession, especially on small businesses, the right way to accomplish that goal?"

If the budget is approved by Congress, drug companies will be required to increase the rebate they pay on medications sold to Medicaid patients from 15 percent to 21 percent. The proposal, which would raise $19.5 billion over 10 years, is likely to spark strong opposition from the industry, which has argued that the current rebate cuts into profits.

Wealthy senior citizens would also be asked to pay higher premiums for Medicare drug coverage, similar to the higher premiums they now pay for physician visits, according to the Obama blueprint.

The budget figures also represent significant shifts in how the United States will pay for medical care.

For example, experts have identified hospital readmissions -- especially for elderly patients -- as a sign of poor care and unnecessary expense. About 18 percent of Medicare patients are readmitted to the hospital within 30 days of an original visit. The new approach would establish flat fees for the first hospitalization and 30 days of follow-up, sometimes done by separate facilities. Hospitals or clinics with high readmission rates could be paid less.

Obama, who is set to host a White House summit on health reform next week, has argued that reining in health spending is critical to the nation's long-term fiscal outlook.

Medicare and Medicaid, the government's two primary safety-net health programs, currently consume 5 percent of the gross domestic product, or $660 billion a year. At their current growth rates, absent restructuring, the two programs will equal 12 percent of the GDP by 2050.

Health-care costs are "one of the major reasons why small businesses close their doors and corporations ship jobs overseas," Obama said in a speech to Congress on Tuesday night.

"This is a cost that now causes a bankruptcy in America every 30 seconds. By the end of the year, it could cause 1.5 million Americans to lose their homes," he said. ". . . Given these facts, we can no longer afford to put health-care reform on hold."